difficult problem
noun phraseUK /ˈdɪfɪkəlt ˈprɒbləm/
US /ˈdɪfɪkəlt ˈprɑːbləm/
A hard puzzle or question that takes a lot of thinking to solve.
The math test had one difficult problem that took me ten minutes to figure out.
OTHER MEANINGS
2. A situation that is hard to deal with or fix.
Finding a babysitter on short notice was a difficult problem for the family.
3. A complicated task in a game or activity that needs skill.
The last level of the game is a difficult problem for most players.
4. A matter that causes worry and needs careful thought.
The broken bridge became a difficult problem for the whole town.